US 6,039,390 · Granted 2000-03-21

The Smart Glass Patent That Makes Windows Tint Themselves

Imagine a window that darkens automatically when the sun gets too bright, without any manual blinds or switches. This patent covers the technology behind "chromogenic" glass—materials that change how much light they let through based on an electrical signal, making windows smarter and more energy-efficient.

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The plain-English version

What it protects

The claim covers the structural design and function of window panels, skylights, sunroofs, and aircraft windows that incorporate chromogenic materials—substances whose optical properties (how transparent or dark they are) change in response to an applied electrical signal. What's protected here is the specific assembly of an outer panel combined with this light-controlling chromogenic layer, as well as related applications like light pipes and window blocks that use the same dynamic darkening principle.

Why it matters

This patent addresses a real problem: controlling heat and glare in buildings and vehicles without traditional blinds, curtains, or shades. By automating the tinting process, chromogenic windows can reduce energy costs for heating and cooling, improve comfort, and eliminate the mechanical wear of manual systems. The technology opens up applications across residential, commercial, and aerospace industries, giving Donnelly Corporation a broad foundation to license or protect variants of smart glass technology.

Real-world use

You might encounter this in a high-end car's sunroof that darkens at a touch, or in modern office buildings where windows automatically adjust their tint throughout the day to reduce glare and save on air conditioning costs.

Original USPTO abstract

A chromogenic window panel assembly, and a chromogenic skylight each includes an outer panel and a chromogenic member having an optical property which varies according to an applied signal. A chromogenic light pipe includes a light harvesting member and a chromogenic member having an optical property which varies according to an applied signal. A chromogenic vehicle sunroof, a chromogenic aircraft window assembly, and a chromogenic window assembly each includes a panel having a particular panel contour corresponding to a surface contour and a chromogenic panel having an optical property which varies according to an applied signal. A chromogenic block includes two panels and a chromogenic panel having an optical property which varies according to an applied signal.

Patent details

Publication number: US 6,039,390
Filing date: 1997-08-20
Grant date: 2000-03-21
Assignee: Donnelly Corporation
Inventor(s): AGRAWAL; ANOOP, TONAZZI; JUAN CARLOS LOPEZ, LECOMPTE; ROBERT STEVEN, BAERTELIN; CARL, FISCHER; DOUGLAS ALAN
CPC class: B32B17/10036

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